Re: [PATCH] sched/fair: use RETRY_TASK in idle_balance

From: kbuild test robot
Date: Fri Apr 27 2018 - 18:49:27 EST

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In reply to: Vincent Guittot: "Re: [PATCH] sched/fair: use RETRY_TASK in idle_balance"
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Hi Vincent,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on v4.17-rc2 next-20180426]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Vincent-Guittot/sched-fair-use-RETRY_TASK-in-idle_balance/20180428-050824
config: x86_64-randconfig-x012-04271426 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64

All warnings (new ones prefixed by >>):

kernel/sched/fair.c: In function 'idle_balance':
>> kernel/sched/fair.c:9865:15: warning: assignment makes integer from pointer without a cast [-Wint-conversion]
pulled_task = RETRY_TASK;
^
Cyclomatic Complexity 5 include/linux/compiler.h:__read_once_size
Cyclomatic Complexity 5 include/linux/compiler.h:__write_once_size
Cyclomatic Complexity 2 arch/x86/include/asm/bitops.h:clear_bit
Cyclomatic Complexity 1 arch/x86/include/asm/bitops.h:constant_test_bit
Cyclomatic Complexity 1 arch/x86/include/asm/bitops.h:variable_test_bit
Cyclomatic Complexity 1 arch/x86/include/asm/bitops.h:fls
Cyclomatic Complexity 1 arch/x86/include/asm/arch_hweight.h:__arch_hweight64
Cyclomatic Complexity 2 include/linux/bitops.h:hweight_long
Cyclomatic Complexity 1 include/linux/log2.h:__ilog2_u32
Cyclomatic Complexity 1 arch/x86/include/asm/current.h:get_current
Cyclomatic Complexity 1 include/linux/list.h:INIT_LIST_HEAD
Cyclomatic Complexity 1 include/linux/list.h:__list_add_valid
Cyclomatic Complexity 1 include/linux/list.h:__list_del_entry_valid
Cyclomatic Complexity 2 include/linux/list.h:__list_add
Cyclomatic Complexity 1 include/linux/list.h:list_add
Cyclomatic Complexity 1 include/linux/list.h:__list_del
Cyclomatic Complexity 2 include/linux/list.h:__list_del_entry
Cyclomatic Complexity 1 include/linux/list.h:list_del_init
Cyclomatic Complexity 1 include/linux/list.h:list_move
Cyclomatic Complexity 1 include/linux/list.h:list_empty
Cyclomatic Complexity 1 arch/x86/include/asm/atomic.h:atomic_read
Cyclomatic Complexity 1 arch/x86/include/asm/atomic64_64.h:atomic64_add
Cyclomatic Complexity 1 include/linux/jump_label.h:static_key_count
Cyclomatic Complexity 3 include/linux/string.h:memset
Cyclomatic Complexity 3 include/linux/bitmap.h:bitmap_and
Cyclomatic Complexity 3 include/linux/bitmap.h:bitmap_intersects
Cyclomatic Complexity 3 include/linux/bitmap.h:bitmap_subset
Cyclomatic Complexity 3 include/linux/bitmap.h:bitmap_weight
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_check
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_first
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_clear_cpu
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_test_cpu
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_and
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_intersects
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_subset
Cyclomatic Complexity 1 include/linux/cpumask.h:cpumask_weight
Cyclomatic Complexity 1 arch/x86/include/asm/paravirt.h:arch_local_irq_restore
Cyclomatic Complexity 1 arch/x86/include/asm/paravirt.h:arch_local_irq_enable
Cyclomatic Complexity 1 include/linux/math64.h:div_u64_rem
Cyclomatic Complexity 1 include/linux/math64.h:div_u64
Cyclomatic Complexity 1 include/linux/math64.h:mul_u64_u32_shr
Cyclomatic Complexity 2 include/linux/thread_info.h:test_ti_thread_flag
Cyclomatic Complexity 1 include/linux/lockdep.h:lock_is_held
Cyclomatic Complexity 1 include/linux/rcupdate.h:rcu_lock_acquire
Cyclomatic Complexity 1 include/linux/rcupdate.h:rcu_lock_release
Cyclomatic Complexity 1 include/linux/rcupdate.h:rcu_read_lock
Cyclomatic Complexity 1 include/linux/rcupdate.h:rcu_read_unlock
Cyclomatic Complexity 1 include/linux/spinlock.h:spin_trylock
Cyclomatic Complexity 1 include/linux/spinlock.h:spin_unlock
Cyclomatic Complexity 1 include/linux/jiffies.h:_msecs_to_jiffies
Cyclomatic Complexity 3 include/linux/jiffies.h:msecs_to_jiffies
Cyclomatic Complexity 1 include/linux/rbtree.h:rb_link_node
Cyclomatic Complexity 1 include/linux/sched.h:task_thread_info
Cyclomatic Complexity 1 include/linux/sched.h:test_tsk_thread_flag
Cyclomatic Complexity 1 include/linux/sched.h:test_tsk_need_resched
Cyclomatic Complexity 1 include/linux/sched.h:task_cpu
Cyclomatic Complexity 1 include/linux/sched/clock.h:local_clock
Cyclomatic Complexity 1 include/linux/sched/cputime.h:get_running_cputimer
Cyclomatic Complexity 2 include/linux/sched/cputime.h:account_group_exec_runtime
Cyclomatic Complexity 1 include/linux/tick.h:tick_nohz_tick_stopped
Cyclomatic Complexity 1 include/linux/sched/topology.h:sched_domain_span
Cyclomatic Complexity 1 include/linux/cgroup.h:task_css_set
Cyclomatic Complexity 1 include/linux/cgroup.h:task_dfl_cgroup
Cyclomatic Complexity 3 include/linux/cgroup.h:cgroup_parent
Cyclomatic Complexity 1 include/linux/cgroup.h:cpuacct_charge
Cyclomatic Complexity 2 include/linux/cgroup.h:cgroup_account_cputime
Cyclomatic Complexity 1 kernel/sched/sched.h:sched_asym_prefer
Cyclomatic Complexity 1 kernel/sched/sched.h:cpu_of
Cyclomatic Complexity 1 kernel/sched/sched.h:__rq_clock_broken
Cyclomatic Complexity 4 kernel/sched/sched.h:assert_clock_updated
Cyclomatic Complexity 4 kernel/sched/sched.h:rq_clock
Cyclomatic Complexity 4 kernel/sched/sched.h:rq_clock_task
Cyclomatic Complexity 5 kernel/sched/sched.h:rq_clock_skip_update
Cyclomatic Complexity 1 kernel/sched/sched.h:rq_pin_lock
Cyclomatic Complexity 2 kernel/sched/sched.h:rq_unpin_lock
Cyclomatic Complexity 1 kernel/sched/sched.h:rq_repin_lock
Cyclomatic Complexity 1 kernel/sched/sched.h:sched_group_span
Cyclomatic Complexity 1 kernel/sched/sched.h:group_balance_mask
Cyclomatic Complexity 1 kernel/sched/sched.h:task_group
Cyclomatic Complexity 1 kernel/sched/sched.h:task_running
Cyclomatic Complexity 1 kernel/sched/sched.h:task_on_rq_queued
Cyclomatic Complexity 1 kernel/sched/sched.h:put_prev_task
Cyclomatic Complexity 4 kernel/sched/sched.h:idle_get_state
Cyclomatic Complexity 1 kernel/sched/sched.h:sched_update_tick_dependency
Cyclomatic Complexity 4 kernel/sched/sched.h:add_nr_running
Cyclomatic Complexity 1 kernel/sched/sched.h:sub_nr_running
Cyclomatic Complexity 1 kernel/sched/sched.h:sched_avg_period
Cyclomatic Complexity 1 kernel/sched/sched.h:hrtick_enabled
Cyclomatic Complexity 1 kernel/sched/sched.h:arch_scale_freq_capacity
Cyclomatic Complexity 4 kernel/sched/sched.h:arch_scale_cpu_capacity
Cyclomatic Complexity 1 kernel/sched/sched.h:rq_lock_irqsave
Cyclomatic Complexity 1 kernel/sched/sched.h:rq_lock_irq
Cyclomatic Complexity 1 kernel/sched/sched.h:rq_lock
Cyclomatic Complexity 1 kernel/sched/sched.h:rq_unlock_irqrestore
Cyclomatic Complexity 1 kernel/sched/sched.h:rq_unlock
Cyclomatic Complexity 1 kernel/sched/sched.h:cpufreq_update_util
Cyclomatic Complexity 1 include/trace/events/sched.h:trace_sched_stat_runtime
Cyclomatic Complexity 1 kernel/sched/fair.c:update_load_add

vim +9865 kernel/sched/fair.c

9757
9758 /*
9759 * idle_balance is called by schedule() if this_cpu is about to become
9760 * idle. Attempts to pull tasks from other CPUs.
9761 */
9762 static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
9763 {
9764 unsigned long next_balance = jiffies + HZ;
9765 int this_cpu = this_rq->cpu;
9766 struct sched_domain *sd;
9767 int pulled_task = 0;
9768 u64 curr_cost = 0;
9769
9770 /*
9771 * We must set idle_stamp _before_ calling idle_balance(), such that we
9772 * measure the duration of idle_balance() as idle time.
9773 */
9774 this_rq->idle_stamp = rq_clock(this_rq);
9775
9776 /*
9777 * Do not pull tasks towards !active CPUs...
9778 */
9779 if (!cpu_active(this_cpu))
9780 return 0;
9781
9782 /*
9783 * This is OK, because current is on_cpu, which avoids it being picked
9784 * for load-balance and preemption/IRQs are still disabled avoiding
9785 * further scheduler activity on it and we're being very careful to
9786 * re-start the picking loop.
9787 */
9788 rq_unpin_lock(this_rq, rf);
9789
9790 if (this_rq->avg_idle < sysctl_sched_migration_cost ||
9791 !this_rq->rd->overload) {
9792
9793 rcu_read_lock();
9794 sd = rcu_dereference_check_sched_domain(this_rq->sd);
9795 if (sd)
9796 update_next_balance(sd, &next_balance);
9797 rcu_read_unlock();
9798
9799 nohz_newidle_balance(this_rq);
9800
9801 goto out;
9802 }
9803
9804 raw_spin_unlock(&this_rq->lock);
9805
9806 update_blocked_averages(this_cpu);
9807 rcu_read_lock();
9808 for_each_domain(this_cpu, sd) {
9809 int continue_balancing = 1;
9810 u64 t0, domain_cost;
9811
9812 if (!(sd->flags & SD_LOAD_BALANCE))
9813 continue;
9814
9815 if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
9816 update_next_balance(sd, &next_balance);
9817 break;
9818 }
9819
9820 if (sd->flags & SD_BALANCE_NEWIDLE) {
9821 t0 = sched_clock_cpu(this_cpu);
9822
9823 pulled_task = load_balance(this_cpu, this_rq,
9824 sd, CPU_NEWLY_IDLE,
9825 &continue_balancing);
9826
9827 domain_cost = sched_clock_cpu(this_cpu) - t0;
9828 if (domain_cost > sd->max_newidle_lb_cost)
9829 sd->max_newidle_lb_cost = domain_cost;
9830
9831 curr_cost += domain_cost;
9832 }
9833
9834 update_next_balance(sd, &next_balance);
9835
9836 /*
9837 * Stop searching for tasks to pull if there are
9838 * now runnable tasks on this rq.
9839 */
9840 if (pulled_task || this_rq->nr_running > 0)
9841 break;
9842 }
9843 rcu_read_unlock();
9844
9845 raw_spin_lock(&this_rq->lock);
9846
9847 if (curr_cost > this_rq->max_idle_balance_cost)
9848 this_rq->max_idle_balance_cost = curr_cost;
9849
9850 /*
9851 * While browsing the domains, we released the rq lock, a task could
9852 * have been enqueued in the meantime. Since we're not going idle,
9853 * pretend we pulled a task.
9854 */
9855 if (this_rq->cfs.h_nr_running && !pulled_task)
9856 pulled_task = 1;
9857
9858 out:
9859 /* Move the next balance forward */
9860 if (time_after(this_rq->next_balance, next_balance))
9861 this_rq->next_balance = next_balance;
9862
9863 /* Is there a task of a high priority class? */
9864 if (this_rq->nr_running != this_rq->cfs.h_nr_running)
> 9865 pulled_task = RETRY_TASK;
9866
9867 if (pulled_task)
9868 this_rq->idle_stamp = 0;
9869
9870 rq_repin_lock(this_rq, rf);
9871
9872 return pulled_task;
9873 }
9874

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Next message: Jonathan Corbet: "Re: [PATCH v3] docs: kernel-parameters.txt: Fix whitespace"
Previous message: Alexei Starovoitov: "Re: [PATCH] bpf: fix misaligned access for BPF_PROG_TYPE_PERF_EVENT program type on x86_32 platform"
In reply to: Vincent Guittot: "Re: [PATCH] sched/fair: use RETRY_TASK in idle_balance"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]